Impedance transformer for amplifier and amplifier including the same

Abstract

An amplifier has an input port, an output port, N gain elements in parallel, an input power splitter coupled between the input port of the amplifier and the input ports of the N gain elements, an output resistor chain extending between the output ports of the first through Nth gain elements, and an output power combiner coupled between the output ports of the N gain elements and the output port of the amplifier. The output power combiner presents a corresponding input impedance to each of the N gain elements. At least two of the input impedances presented by the output power combiner to the N gain elements are substantially different from each other.

1. An amplifier, comprising:
 an input terminal adapted to receive an input signal to be amplified; 
 an output terminal adapted to output an amplified output signal; 
 first, second, third, and fourth gain elements each having an input port and an output port; 
 an input power splitter coupled to the input terminal of the amplifier and adapted to split the input power and apply the split input signal to the input ports of the first through fourth gain elements; 
 an output resistor chain comprising three resistors extending between and connecting the output ports of the first through fourth gain elements; and 
 an output power combiner coupled to the output ports of the four gain elements and adapted to combine output signals from the four gain elements and provide the amplified output signal to the output terminal of the amplifier, 
 wherein the output power combiner comprises,
 a first capacitor connected between a first combiner node and a fixed voltage, 
 a second capacitor connected between a second combiner node and the fixed voltage, 
 a first inductor connected between the output port of the first gain element and the first combiner node, 
 a second inductor connected between the output port of the second gain element and the first combiner node, 
 a third inductor connected between the output port of the third gain element and a second combiner node, 
 a fourth inductor connected between the output port of the fourth gain element and the second combiner node, and 
 an output stage coupling the first and second combiner nodes to the output port of the amplifier, 
 
 wherein at least two of the first, second, third, and fourth inductors have substantially different inductance values from each other. 
 
   
   
     2. The amplifier of  claim 1 , wherein the first and fourth inductors have substantially the same inductance as each other, and the second and third inductors have substantially the same inductance as each other, and wherein the inductance of the first and fourth inductors is substantially smaller than the inductance of the second and third inductors. 
   
   
     3. The amplifier of  claim 1 , further comprising an input resistor chain comprising three resistors extending between and connecting the input ports of the first through fourth gain elements. 
   
   
     4. The amplifier of  claim 3 , wherein the input power splitter comprises:
 a third capacitor connected between a first splitter node and the fixed voltage, 
 a fourth capacitor connected between a second splitter node and the fixed voltage, 
 a fifth inductor connected between the input port of the first gain element and the first splitter node, 
 a sixth inductor connected between the input port of the second gain element and the first splitter node, 
 a seventh inductor connected between the input port of the third gain element and a second splitter node, 
 an eighth inductor connected between the input port of the fourth gain element and the second splitter node, and 
 an input stage coupling the input terminal of the amplifier to the first and second splitter nodes, 
 wherein at least two of the fifth, sixth, seventh, and eighth inductors have substantially different inductance values from each other. 
 
   
   
     5. The amplifier of  claim 4 , wherein the fifth and eighth inductors have substantially the same inductance as each other, and the sixth and seventh inductors have substantially the same inductance as each other, and wherein the inductance of the fifth and eighth inductors is substantially smaller than the inductance of the sixth and seventh inductors. 
   
   
     6. The amplifier of  claim 1 , wherein the four gain elements comprise four field effect transistors having substantially the same size as each other. 
   
   
     7. An amplifier, comprising:
 an input terminal adapted to receive an input signal to be amplified; 
 an output terminal adapted to output an amplified output signal; 
 first, second, third, and fourth gain elements each having an input port and an output port; 
 an input power splitter coupled to the input terminal of the amplifier and adapted to split the input power and apply the split input signal to the input ports of the four gain elements; 
 an output resistor chain comprising three resistors extending between and connecting the output ports of the first through fourth gain elements; and 
 an output power combiner coupled to the output ports of the four gain elements and adapted to combine output signals from the four gain elements and provide the amplified output signal to the output terminal of the amplifier, 
 wherein the output power combiner comprises,
 a first capacitor connected between a first combiner node and a fixed voltage, 
 a second capacitor connected between a second combiner node and the fixed voltage, 
 a first inductor connected between the output port of the first gain element and the first combiner node, 
 a second inductor connected between the output port of the second gain element and the first combiner node, 
 a third inductor connected between the output port of the third gain element and a second combiner node, 
 a fourth inductor connected between the output port of the fourth gain element and the second combiner node, 
 a fifth inductor connected between the output port of the first gain element and the fixed voltage, 
 a sixth inductor connected between the output port of the second gain element and the fixed voltage, 
 a seventh inductor connected between the output port of the third gain element and the fixed voltage, 
 an eighth inductor connected between the output port of the fourth gain element and the fixed voltage, and 
 an output stage coupling the first and second combiner nodes to the output terminal of the amplifier, 
 
 wherein the first, second, third, and fourth inductors have substantially the same inductance values as each other, and 
 wherein at least two of the fifth, sixth, seventh, and eighth inductors have substantially different inductance values from each other. 
 
   
   
     8. The amplifier of  claim 7 , wherein the fifth and eighth inductors have substantially the same inductance as each other, and the sixth and seventh inductors have substantially the same inductance as each other, and wherein the inductance of the fifth and eighth inductors is substantially greater than the inductance of the sixth and seventh inductors. 
   
   
     9. The amplifier of  claim 7 , further comprising an input resistor chain comprising three resistors extending between and connecting the input ports of the first through fourth gain elements. 
   
   
     10. The amplifier of  claim 9 , wherein the input power splitter comprises:
 a third capacitor connected between a first splitter node and the fixed voltage, 
 a fourth capacitor connected between a second splitter node and the fixed voltage, 
 a ninth inductor connected between the input port of the first gain element and the first splitter node, 
 a tenth inductor connected between the input port of the second gain element and the first splitter node, 
 an eleventh inductor connected between the input port of the third gain element and a second splitter node, 
 a twelfth inductor connected between the input port of the fourth gain element and the second splitter node, and 
 an input stage coupling the input terminal of the amplifier to the first and second splitter nodes, 
 wherein at least two of the ninth, tenth, eleventh, and twelfth inductors have substantially different inductance values from each other. 
 
   
   
     11. The amplifier of  claim 10 , wherein the ninth and twelfth inductors have substantially the same inductance as each other, and the tenth and eleventh inductors have substantially the same inductance as each other, and wherein the inductance of the ninth and twelfth inductors is substantially greater than the inductance of the tenth and eleventh inductors. 
   
   
     12. The amplifier of  claim 7 , wherein the four gain elements comprise four field effect transistors having substantially the same size as each other. 
   
   
     13. An amplifier, comprising:
 an input terminal adapted to receive an input signal to be amplified; 
 an output terminal adapted to output an amplified output signal; 
 first through N th  gain elements each having an input port and an output port; 
 an input power splitter coupled to the input terminal of the amplifier and adapted to split the input power and apply the split input signal to the input ports of the first through N th  gain elements; 
 an output resistor chain comprising N−1 resistors extending between and connecting the output ports of the first through N th  gain elements; and 
 an output power combiner coupled to the output ports of the N gain elements and adapted to combine output signals from the N gain elements and provide the amplified output signal to the output terminal of the amplifier, 
 wherein the output power combiner presents a corresponding input impedance to each of the N gain elements, and 
 wherein at least two of the input impedances presented by the output power combiner to the N gain elements are substantially different from each other. 
 
   
   
     14. The amplifier of  claim 13 , wherein the input impedances presented by the output power combiner to the first and N th  gain elements are substantially the same as each other, and the input impedances presented by the output power combiner to the second through (N−1) th  gain elements are substantially the same as each other, and wherein the input impedances presented by the output power combiner to the first and N th  gain elements is substantially greater than the input impedances presented by the output power combiner to the second through (N−1) th  gain elements. 
   
   
     15. The amplifier of  claim 14 , wherein a difference between the input impedances presented by the output power combiner to the first and N th  gain elements, and the input impedances presented by the output power combiner to the second through (N−1) th  gain elements, compensates for a difference in impedances of the output resistor chain seen by the first and N th  gain elements compared to impedances of the output resistor chain seen by the second and through (N−1) th  gain elements. 
   
   
     16. The amplifier of  claim 13 , further comprising an input resistor chain comprising N−1 resistors extending between and connecting the input ports of the first though N th  gain elements. 
   
   
     17. The amplifier of  claim 16 , wherein the input power splitter presents a corresponding output impedance to each of the N gain elements, and wherein at least two of the output impedances presented by the input power splitter to the N gain elements are substantially different from each other. 
   
   
     18. The amplifier of  claim 13 , wherein the N gain elements comprise N field effect transistors having substantially the same size as each other.